This invention relates to N-(2,2,6,6-tetraalkyl-4-piperidinyl)amide-hydrazides of dicarboxylic acids which contain a hindered amine light stabilizing group (photooxidative stabilizer) and a reactive hydrazide group (heat stabilizer). In addition, this invention relates to the stabilization of polymeric systems against the degradative effects of heat and/or light.
Polymers such as polyolefins (e.g., polyethylene, polypropylene, etc.) styrenics (e.g., polystyrene, rubber modified polystyrene, ABS, MBS, etc.), polyvinyl chloride, polycarbonates, polyesters, polyphenylene ethers, and polyamides, for example, are subject to degradation and discoloration upon exposure to heat and/or light with consequent deterioration of their mechanical properties.
Various stabilizers have been proposed to inhibit such deterioration. Hindered piperidine compounds have found extensive use in the photostabilization of polyolefins. Hydrazides have been used to prevent deterioration of polyolefins by heat, oxidation, or heavy metal contamination. Derivatives of hydrazides are also commercially available for use as polymer stabilizers. (See Encyclopedia of Polymer Science and Engineering, 2nd Ed. Vol. 2, pp. 83-84).
Four examples were found in the literature where the hindered amine moiety and the hydrazide moiety (--R--C(.dbd.O)--NH--NH2, where R is not O, N, or S) are present in the same molecule. ##STR1##
None of these prior art hydrazides fall under general structure I of the present invention.